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<a href="cong__ctl__classic__bw_8cpp.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a id="l00001" name="l00001"></a><span class="lineno">    1</span><span class="comment">/* Flow</span></div>
<div class="line"><a id="l00002" name="l00002"></a><span class="lineno">    2</span><span class="comment"> * Copyright 2023 Akamai Technologies, Inc.</span></div>
<div class="line"><a id="l00003" name="l00003"></a><span class="lineno">    3</span><span class="comment"> *</span></div>
<div class="line"><a id="l00004" name="l00004"></a><span class="lineno">    4</span><span class="comment"> * Licensed under the Apache License, Version 2.0 (the</span></div>
<div class="line"><a id="l00005" name="l00005"></a><span class="lineno">    5</span><span class="comment"> * &quot;License&quot;); you may not use this file except in</span></div>
<div class="line"><a id="l00006" name="l00006"></a><span class="lineno">    6</span><span class="comment"> * compliance with the License.  You may obtain a copy</span></div>
<div class="line"><a id="l00007" name="l00007"></a><span class="lineno">    7</span><span class="comment"> * of the License at</span></div>
<div class="line"><a id="l00008" name="l00008"></a><span class="lineno">    8</span><span class="comment"> *</span></div>
<div class="line"><a id="l00009" name="l00009"></a><span class="lineno">    9</span><span class="comment"> *   https://www.apache.org/licenses/LICENSE-2.0</span></div>
<div class="line"><a id="l00010" name="l00010"></a><span class="lineno">   10</span><span class="comment"> *</span></div>
<div class="line"><a id="l00011" name="l00011"></a><span class="lineno">   11</span><span class="comment"> * Unless required by applicable law or agreed to in</span></div>
<div class="line"><a id="l00012" name="l00012"></a><span class="lineno">   12</span><span class="comment"> * writing, software distributed under the License is</span></div>
<div class="line"><a id="l00013" name="l00013"></a><span class="lineno">   13</span><span class="comment"> * distributed on an &quot;AS IS&quot; BASIS, WITHOUT WARRANTIES OR</span></div>
<div class="line"><a id="l00014" name="l00014"></a><span class="lineno">   14</span><span class="comment"> * CONDITIONS OF ANY KIND, either express or implied.</span></div>
<div class="line"><a id="l00015" name="l00015"></a><span class="lineno">   15</span><span class="comment"> * See the License for the specific language governing</span></div>
<div class="line"><a id="l00016" name="l00016"></a><span class="lineno">   16</span><span class="comment"> * permissions and limitations under the License. */</span></div>
<div class="line"><a id="l00017" name="l00017"></a><span class="lineno">   17</span><span class="comment"></span> </div>
<div class="line"><a id="l00018" name="l00018"></a><span class="lineno">   18</span><span class="comment">/// @file</span></div>
<div class="line"><a id="l00019" name="l00019"></a><span class="lineno">   19</span><span class="comment"></span><span class="preprocessor">#include &quot;<a class="code" href="cong__ctl__classic__bw_8hpp.html">flow/net_flow/detail/cong_ctl/cong_ctl_classic_bw.hpp</a>&quot;</span></div>
<div class="line"><a id="l00020" name="l00020"></a><span class="lineno">   20</span> </div>
<div class="line"><a id="l00021" name="l00021"></a><span class="lineno">   21</span><span class="keyword">namespace </span><a class="code hl_namespace" href="namespaceflow_1_1net__flow.html">flow::net_flow</a></div>
<div class="line"><a id="l00022" name="l00022"></a><span class="lineno">   22</span>{</div>
<div class="line"><a id="l00023" name="l00023"></a><span class="lineno">   23</span><span class="comment">// Static initializations.</span></div>
<div class="line"><a id="l00024" name="l00024"></a><span class="lineno">   24</span> </div>
<div class="line"><a id="l00025" name="l00025"></a><span class="lineno">   25</span><span class="comment">// Use conservative start value which will be overridden with the next ACK.  (Value taken from Linux tcp_westwood.c.)</span></div>
<div class="line"><a id="l00026" name="l00026"></a><span class="lineno">   26</span><span class="keyword">const</span> <a class="code hl_typedef" href="classflow_1_1net__flow_1_1Send__bandwidth__estimator.html#a1e5e59588c6683d56866e49e5fd2980e">Send_bandwidth_estimator::Time_unit</a> <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a07b264d895ef7eb343d6d503d12e63d0">Congestion_control_classic_with_bandwidth_est::S_INIT_RTT_MIN</a></div>
<div class="line"><a id="l00027" name="l00027"></a><span class="lineno">   27</span>  = boost::chrono::seconds(20);</div>
<div class="line"><a id="l00028" name="l00028"></a><span class="lineno">   28</span> </div>
<div class="line"><a id="l00029" name="l00029"></a><span class="lineno">   29</span><span class="comment">// Implementations.</span></div>
<div class="line"><a id="l00030" name="l00030"></a><span class="lineno">   30</span> </div>
<div class="line"><a id="l00031" name="l00031"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#ad0090c57a7877701be584c006c9db329">   31</a></span><a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#ad0090c57a7877701be584c006c9db329">Congestion_control_classic_with_bandwidth_est::Congestion_control_classic_with_bandwidth_est</a></div>
<div class="line"><a id="l00032" name="l00032"></a><span class="lineno">   32</span>  (<a class="code hl_class" href="classflow_1_1log_1_1Logger.html">log::Logger</a>* logger_ptr, <a class="code hl_typedef" href="classflow_1_1util_1_1Shared__ptr__alias__holder.html#aef7998db71c60eeb5d1e3d1a97c14886">Peer_socket::Const_ptr</a> sock) :</div>
<div class="line"><a id="l00033" name="l00033"></a><span class="lineno">   33</span> </div>
<div class="line"><a id="l00034" name="l00034"></a><span class="lineno">   34</span>  <a class="code hl_class" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html">Congestion_control_strategy</a>(logger_ptr, sock),</div>
<div class="line"><a id="l00035" name="l00035"></a><span class="lineno">   35</span>  <span class="comment">// Initialize the basics (CWND, SSTHRESH, etc.) in the usual way.</span></div>
<div class="line"><a id="l00036" name="l00036"></a><span class="lineno">   36</span>  m_classic_data(logger_ptr, sock),</div>
<div class="line"><a id="l00037" name="l00037"></a><span class="lineno">   37</span>  <span class="comment">// See comment on S_INIT_RTT_MIN declaration inside class.</span></div>
<div class="line"><a id="l00038" name="l00038"></a><span class="lineno">   38</span>  m_rtt_min(S_INIT_RTT_MIN),</div>
<div class="line"><a id="l00039" name="l00039"></a><span class="lineno">   39</span>  <span class="comment">// Trigger S_INIT_RTT_MIN to be disregarded as soon as we get an ACK.</span></div>
<div class="line"><a id="l00040" name="l00040"></a><span class="lineno">   40</span>  m_reset_rtt_min(true)</div>
<div class="line"><a id="l00041" name="l00041"></a><span class="lineno">   41</span>{</div>
<div class="line"><a id="l00042" name="l00042"></a><span class="lineno">   42</span>  <span class="comment">// Nothing.</span></div>
<div class="line"><a id="l00043" name="l00043"></a><span class="lineno">   43</span>}</div>
<div class="line"><a id="l00044" name="l00044"></a><span class="lineno">   44</span> </div>
<div class="line"><a id="l00045" name="l00045"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#af49a3fe6d8bb1ec32ac245faed17e842">   45</a></span><span class="keywordtype">size_t</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#af49a3fe6d8bb1ec32ac245faed17e842">Congestion_control_classic_with_bandwidth_est::congestion_window_bytes</a>() const <span class="comment">// Virtual.</span></div>
<div class="line"><a id="l00046" name="l00046"></a><span class="lineno">   46</span>{</div>
<div class="line"><a id="l00047" name="l00047"></a><span class="lineno">   47</span>  <span class="keywordflow">return</span> <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#aeb3b683eed3fcd8af27323fc747abb03">m_classic_data</a>.<a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#adbda0ed3747b1eea62f4d790c37dbe46">congestion_window_bytes</a>();</div>
<div class="line"><a id="l00048" name="l00048"></a><span class="lineno">   48</span>}</div>
<div class="line"><a id="l00049" name="l00049"></a><span class="lineno">   49</span> </div>
<div class="line"><a id="l00050" name="l00050"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a8d0e32a67aa333ab15a5b166a2913260">   50</a></span><span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a8d0e32a67aa333ab15a5b166a2913260">Congestion_control_classic_with_bandwidth_est::on_individual_ack</a></div>
<div class="line"><a id="l00051" name="l00051"></a><span class="lineno">   51</span>       (<span class="keyword">const</span> <a class="code hl_typedef" href="namespaceflow.html#a48799f1263cdeedec125be51a3db2b79">Fine_duration</a>&amp; packet_rtt,</div>
<div class="line"><a id="l00052" name="l00052"></a><span class="lineno">   52</span>        [[maybe_unused]] <span class="keyword">const</span> <span class="keywordtype">size_t</span> bytes, [[maybe_unused]] <span class="keyword">const</span> <span class="keywordtype">size_t</span> sent_cwnd_bytes) <span class="comment">// Virtual.</span></div>
<div class="line"><a id="l00053" name="l00053"></a><span class="lineno">   53</span>{</div>
<div class="line"><a id="l00054" name="l00054"></a><span class="lineno">   54</span>  <span class="keyword">using </span>boost::chrono::ceil;</div>
<div class="line"><a id="l00055" name="l00055"></a><span class="lineno">   55</span>  <span class="keyword">using </span>boost::chrono::round;</div>
<div class="line"><a id="l00056" name="l00056"></a><span class="lineno">   56</span>  <span class="keyword">using </span>boost::chrono::milliseconds;</div>
<div class="line"><a id="l00057" name="l00057"></a><span class="lineno">   57</span> </div>
<div class="line"><a id="l00058" name="l00058"></a><span class="lineno">   58</span>  <span class="keyword">const</span> <a class="code hl_typedef" href="classflow_1_1util_1_1Shared__ptr__alias__holder.html#aef7998db71c60eeb5d1e3d1a97c14886">Peer_socket::Const_ptr</a> sock = <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a3e9786f9e5f170ca23135a2a815bc3f4">socket</a>();</div>
<div class="line"><a id="l00059" name="l00059"></a><span class="lineno">   59</span> </div>
<div class="line"><a id="l00060" name="l00060"></a><span class="lineno">   60</span>  <span class="comment">/* As in the reference implementation (Linux&#39;s tcp_westwood.c), trivially maintain the lowest</span></div>
<div class="line"><a id="l00061" name="l00061"></a><span class="lineno">   61</span><span class="comment">   * known individual RTT.  The only deviation from that is certain events can cause the existing</span></div>
<div class="line"><a id="l00062" name="l00062"></a><span class="lineno">   62</span><span class="comment">   * minimum RTT to be invalidated, starting a new sequence.</span></div>
<div class="line"><a id="l00063" name="l00063"></a><span class="lineno">   63</span><span class="comment">   *</span></div>
<div class="line"><a id="l00064" name="l00064"></a><span class="lineno">   64</span><span class="comment">   * Another caveat concerns units.  Due to the math in congestion_window_adjust(), we store</span></div>
<div class="line"><a id="l00065" name="l00065"></a><span class="lineno">   65</span><span class="comment">   * m_rtt_min in Send_bandwidth_estimator-friendly units, likely less fine than those used in</span></div>
<div class="line"><a id="l00066" name="l00066"></a><span class="lineno">   66</span><span class="comment">   * Fine_duration but fine enough (see that alias&#39;s doc header for discussion).  In converting,</span></div>
<div class="line"><a id="l00067" name="l00067"></a><span class="lineno">   67</span><span class="comment">   * round up as a convention, if only to try to avoid 0.  @todo Why is that really needed?</span></div>
<div class="line"><a id="l00068" name="l00068"></a><span class="lineno">   68</span><span class="comment">   * There&#39;s no division by this number.... */</span></div>
<div class="line"><a id="l00069" name="l00069"></a><span class="lineno">   69</span> </div>
<div class="line"><a id="l00070" name="l00070"></a><span class="lineno">   70</span>  <span class="keyword">const</span> <a class="code hl_typedef" href="classflow_1_1net__flow_1_1Send__bandwidth__estimator.html#a1e5e59588c6683d56866e49e5fd2980e">Send_bandwidth_estimator::Time_unit</a> packet_rtt_conv = ceil&lt;Send_bandwidth_estimator::Time_unit&gt;(packet_rtt);</div>
<div class="line"><a id="l00071" name="l00071"></a><span class="lineno">   71</span> </div>
<div class="line"><a id="l00072" name="l00072"></a><span class="lineno">   72</span>  <span class="keywordflow">if</span> (<a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a5b3a333ae29bd009cd22919c1e01c19f">m_reset_rtt_min</a>)</div>
<div class="line"><a id="l00073" name="l00073"></a><span class="lineno">   73</span>  {</div>
<div class="line"><a id="l00074" name="l00074"></a><span class="lineno">   74</span>    <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a5b3a333ae29bd009cd22919c1e01c19f">m_reset_rtt_min</a> = <span class="keyword">false</span>;</div>
<div class="line"><a id="l00075" name="l00075"></a><span class="lineno">   75</span>    <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#aac8260cf710dc42843a478873ed8b649">m_rtt_min</a> = packet_rtt_conv;</div>
<div class="line"><a id="l00076" name="l00076"></a><span class="lineno">   76</span> </div>
<div class="line"><a id="l00077" name="l00077"></a><span class="lineno">   77</span>    <a class="code hl_define" href="log_8hpp.html#affcf2e4c496ce3f42adf981669c623b8">FLOW_LOG_TRACE</a>(<span class="stringliteral">&quot;cong_ctl|bw_est [&quot;</span> &lt;&lt; sock &lt;&lt; <span class="stringliteral">&quot;] update: RTT event; reset rtt_min &quot;</span></div>
<div class="line"><a id="l00078" name="l00078"></a><span class="lineno">   78</span>                   <span class="stringliteral">&quot;to [&quot;</span> &lt;&lt; round&lt;milliseconds&gt;(<a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#aac8260cf710dc42843a478873ed8b649">m_rtt_min</a>) &lt;&lt; <span class="stringliteral">&quot;].&quot;</span>);</div>
<div class="line"><a id="l00079" name="l00079"></a><span class="lineno">   79</span>  }</div>
<div class="line"><a id="l00080" name="l00080"></a><span class="lineno">   80</span>  <span class="keywordflow">else</span></div>
<div class="line"><a id="l00081" name="l00081"></a><span class="lineno">   81</span>  {</div>
<div class="line"><a id="l00082" name="l00082"></a><span class="lineno">   82</span>    <span class="keyword">const</span> milliseconds prev_rtt_min = round&lt;milliseconds&gt;(<a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#aac8260cf710dc42843a478873ed8b649">m_rtt_min</a>);</div>
<div class="line"><a id="l00083" name="l00083"></a><span class="lineno">   83</span> </div>
<div class="line"><a id="l00084" name="l00084"></a><span class="lineno">   84</span>    <span class="keywordflow">if</span> (packet_rtt_conv &lt; <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#aac8260cf710dc42843a478873ed8b649">m_rtt_min</a>)</div>
<div class="line"><a id="l00085" name="l00085"></a><span class="lineno">   85</span>    {</div>
<div class="line"><a id="l00086" name="l00086"></a><span class="lineno">   86</span>      <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#aac8260cf710dc42843a478873ed8b649">m_rtt_min</a> = packet_rtt_conv;</div>
<div class="line"><a id="l00087" name="l00087"></a><span class="lineno">   87</span>    }</div>
<div class="line"><a id="l00088" name="l00088"></a><span class="lineno">   88</span> </div>
<div class="line"><a id="l00089" name="l00089"></a><span class="lineno">   89</span>    <a class="code hl_define" href="log_8hpp.html#affcf2e4c496ce3f42adf981669c623b8">FLOW_LOG_TRACE</a>(<span class="stringliteral">&quot;cong_ctl|bw_est [&quot;</span> &lt;&lt; sock &lt;&lt; <span class="stringliteral">&quot;] update: RTT event; set rtt_min = &quot;</span></div>
<div class="line"><a id="l00090" name="l00090"></a><span class="lineno">   90</span>                   <span class="stringliteral">&quot;min[&quot;</span> &lt;&lt; prev_rtt_min</div>
<div class="line"><a id="l00091" name="l00091"></a><span class="lineno">   91</span>                   &lt;&lt; <span class="stringliteral">&quot;, &quot;</span> &lt;&lt; round&lt;milliseconds&gt;(packet_rtt_conv) &lt;&lt; <span class="stringliteral">&quot;] &quot;</span></div>
<div class="line"><a id="l00092" name="l00092"></a><span class="lineno">   92</span>                   <span class="stringliteral">&quot;= [&quot;</span> &lt;&lt; round&lt;milliseconds&gt;(<a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#aac8260cf710dc42843a478873ed8b649">m_rtt_min</a>) &lt;&lt; <span class="stringliteral">&quot;].&quot;</span>);</div>
<div class="line"><a id="l00093" name="l00093"></a><span class="lineno">   93</span>  }</div>
<div class="line"><a id="l00094" name="l00094"></a><span class="lineno">   94</span>} <span class="comment">// Congestion_control_classic_with_bandwidth_est::on_individual_ack()</span></div>
<div class="line"><a id="l00095" name="l00095"></a><span class="lineno">   95</span> </div>
<div class="line"><a id="l00096" name="l00096"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a83ee8438d6033c26a6af03b9dd173dc3">   96</a></span><span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a83ee8438d6033c26a6af03b9dd173dc3">Congestion_control_classic_with_bandwidth_est::on_acks</a>([[maybe_unused]] <span class="keywordtype">size_t</span> bytes,</div>
<div class="line"><a id="l00097" name="l00097"></a><span class="lineno">   97</span>                                                            [[maybe_unused]] <span class="keywordtype">size_t</span> packets) <span class="comment">// Virtual.</span></div>
<div class="line"><a id="l00098" name="l00098"></a><span class="lineno">   98</span>{</div>
<div class="line"><a id="l00099" name="l00099"></a><span class="lineno">   99</span>  <span class="comment">// Same as Congestion_control_classic; we are only different upon loss detection.</span></div>
<div class="line"><a id="l00100" name="l00100"></a><span class="lineno">  100</span>  <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#aeb3b683eed3fcd8af27323fc747abb03">m_classic_data</a>.<a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#ab3e34468efdf4d9e5b29eceb1fe84665">on_acks</a>(bytes); <span class="comment">// Will log.</span></div>
<div class="line"><a id="l00101" name="l00101"></a><span class="lineno">  101</span>}</div>
<div class="line"><a id="l00102" name="l00102"></a><span class="lineno">  102</span> </div>
<div class="line"><a id="l00103" name="l00103"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a942ce2561d6d2bbbb8faa8160a772416">  103</a></span><span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a942ce2561d6d2bbbb8faa8160a772416">Congestion_control_classic_with_bandwidth_est::on_loss_event</a>([[maybe_unused]] <span class="keywordtype">size_t</span> bytes,</div>
<div class="line"><a id="l00104" name="l00104"></a><span class="lineno">  104</span>                                                                  [[maybe_unused]] <span class="keywordtype">size_t</span> packets) <span class="comment">// Virtual.</span></div>
<div class="line"><a id="l00105" name="l00105"></a><span class="lineno">  105</span>{</div>
<div class="line"><a id="l00106" name="l00106"></a><span class="lineno">  106</span>  <span class="comment">/* Node has detected at least some lost bytes (at least one dropped packet), or at least so it</span></div>
<div class="line"><a id="l00107" name="l00107"></a><span class="lineno">  107</span><span class="comment">   * thinks, but it&#39;s not a &quot;major&quot; (Drop Timeout-based) loss.  At its core, we follow classic Reno,</span></div>
<div class="line"><a id="l00108" name="l00108"></a><span class="lineno">  108</span><span class="comment">   * reset the available pipe (CWND) to some probably lower value; and set SSTHRESH to that same</span></div>
<div class="line"><a id="l00109" name="l00109"></a><span class="lineno">  109</span><span class="comment">   * value, so that we immediately begin congestion avoidance (slow linear increase in CWND), and so</span></div>
<div class="line"><a id="l00110" name="l00110"></a><span class="lineno">  110</span><span class="comment">   * that if we later enter slow start for whatever reason, it will end at this CWND value (unless</span></div>
<div class="line"><a id="l00111" name="l00111"></a><span class="lineno">  111</span><span class="comment">   * something else changes SSTHRESH before then of course).</span></div>
<div class="line"><a id="l00112" name="l00112"></a><span class="lineno">  112</span><span class="comment">   *</span></div>
<div class="line"><a id="l00113" name="l00113"></a><span class="lineno">  113</span><span class="comment">   * Of course this is not Reno but instead &quot;classic with bandwidth estimation.&quot;  The difference is</span></div>
<div class="line"><a id="l00114" name="l00114"></a><span class="lineno">  114</span><span class="comment">   * that we set CWND not to 1/2 (or any other constant) of anything but rather to our best guess on</span></div>
<div class="line"><a id="l00115" name="l00115"></a><span class="lineno">  115</span><span class="comment">   * what the pipe can currently take.  The standard formula is CWND = B * RTT, where B is the</span></div>
<div class="line"><a id="l00116" name="l00116"></a><span class="lineno">  116</span><span class="comment">   * available bandwidth, and RTT is the delay of the pipe.  RTT is taken to be the minimum RTT</span></div>
<div class="line"><a id="l00117" name="l00117"></a><span class="lineno">  117</span><span class="comment">   * observed on the pipe, which should represent the &quot;true&quot; delay.  B is estimated using</span></div>
<div class="line"><a id="l00118" name="l00118"></a><span class="lineno">  118</span><span class="comment">   * Send_bandwidth_estimator.  Altogether this is the Westwood+ algorithm, but the main part of it</span></div>
<div class="line"><a id="l00119" name="l00119"></a><span class="lineno">  119</span><span class="comment">   * is the B estimation, which has been separated into Send_bandwidth_estimator, because its</span></div>
<div class="line"><a id="l00120" name="l00120"></a><span class="lineno">  120</span><span class="comment">   * results may be useful outside of congestion control.  For more info on Westwood+ see that</span></div>
<div class="line"><a id="l00121" name="l00121"></a><span class="lineno">  121</span><span class="comment">   * class&#39;s doc header.</span></div>
<div class="line"><a id="l00122" name="l00122"></a><span class="lineno">  122</span><span class="comment">   *</span></div>
<div class="line"><a id="l00123" name="l00123"></a><span class="lineno">  123</span><span class="comment">   * As a reference implementation of the CWND = B * RTT formula, we use Linux kernel&#39;s</span></div>
<div class="line"><a id="l00124" name="l00124"></a><span class="lineno">  124</span><span class="comment">   * tcp_westwood.c, which was implemented by the inventors of the algorithm. */</span></div>
<div class="line"><a id="l00125" name="l00125"></a><span class="lineno">  125</span> </div>
<div class="line"><a id="l00126" name="l00126"></a><span class="lineno">  126</span>  <span class="keyword">const</span> <span class="keywordtype">size_t</span> new_wnd_bytes = <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a9650086c28de7e9ed9fdaecaf9f183a6">congestion_window_adjusted_bytes</a>();</div>
<div class="line"><a id="l00127" name="l00127"></a><span class="lineno">  127</span> </div>
<div class="line"><a id="l00128" name="l00128"></a><span class="lineno">  128</span>  <span class="keyword">const</span> <a class="code hl_typedef" href="classflow_1_1util_1_1Shared__ptr__alias__holder.html#aef7998db71c60eeb5d1e3d1a97c14886">Peer_socket::Const_ptr</a> sock = <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a3e9786f9e5f170ca23135a2a815bc3f4">socket</a>();</div>
<div class="line"><a id="l00129" name="l00129"></a><span class="lineno">  129</span>  <a class="code hl_define" href="log_8hpp.html#affcf2e4c496ce3f42adf981669c623b8">FLOW_LOG_TRACE</a>(<span class="stringliteral">&quot;cong_ctl|bw_est [&quot;</span> &lt;&lt; sock &lt;&lt; <span class="stringliteral">&quot;] update: loss event; &quot;</span></div>
<div class="line"><a id="l00130" name="l00130"></a><span class="lineno">  130</span>                 <span class="stringliteral">&quot;set sl_st_thresh=cong_wnd to [&quot;</span> &lt;&lt; sock-&gt;bytes_blocks_str(new_wnd_bytes) &lt;&lt; <span class="stringliteral">&quot;].&quot;</span>);</div>
<div class="line"><a id="l00131" name="l00131"></a><span class="lineno">  131</span> </div>
<div class="line"><a id="l00132" name="l00132"></a><span class="lineno">  132</span>  <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#aeb3b683eed3fcd8af27323fc747abb03">m_classic_data</a>.<a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a79e85a67e583b74cc414524d53650892">on_congestion_event</a>(new_wnd_bytes, new_wnd_bytes); <span class="comment">// Will log but not enough (so log the above).</span></div>
<div class="line"><a id="l00133" name="l00133"></a><span class="lineno">  133</span> </div>
<div class="line"><a id="l00134" name="l00134"></a><span class="lineno">  134</span>  <span class="comment">// Beyond that, nothing else.  See Congestion_control_classic comments in same spot which apply equally.</span></div>
<div class="line"><a id="l00135" name="l00135"></a><span class="lineno">  135</span>} <span class="comment">// Congestion_control_classic_with_bandwidth_est::on_loss_event()</span></div>
<div class="line"><a id="l00136" name="l00136"></a><span class="lineno">  136</span> </div>
<div class="line"><a id="l00137" name="l00137"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a3358f8b8700d5427a5163f2f480b2e8d">  137</a></span><span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a3358f8b8700d5427a5163f2f480b2e8d">Congestion_control_classic_with_bandwidth_est::on_drop_timeout</a>([[maybe_unused]] <span class="keywordtype">size_t</span> bytes,</div>
<div class="line"><a id="l00138" name="l00138"></a><span class="lineno">  138</span>                                                                    [[maybe_unused]] <span class="keywordtype">size_t</span> packets) <span class="comment">// Virtual.</span></div>
<div class="line"><a id="l00139" name="l00139"></a><span class="lineno">  139</span>{</div>
<div class="line"><a id="l00140" name="l00140"></a><span class="lineno">  140</span>  <span class="comment">/* Node has detected a major loss event in the form of a Drop Timeout.  As in on_loss_event(), do</span></div>
<div class="line"><a id="l00141" name="l00141"></a><span class="lineno">  141</span><span class="comment">   * the same thing as Congestion_control_classic does except that SSTHRESH is not 1/2 of anything</span></div>
<div class="line"><a id="l00142" name="l00142"></a><span class="lineno">  142</span><span class="comment">   * but rather selected based on the bandwidth estimation.</span></div>
<div class="line"><a id="l00143" name="l00143"></a><span class="lineno">  143</span><span class="comment">   *</span></div>
<div class="line"><a id="l00144" name="l00144"></a><span class="lineno">  144</span><span class="comment">   * Additionally, a major loss event implies that the properties of the pipe may have changed</span></div>
<div class="line"><a id="l00145" name="l00145"></a><span class="lineno">  145</span><span class="comment">   * (e.g., different IP route).  Therefore we (as the reference implementation, Linux&#39;s</span></div>
<div class="line"><a id="l00146" name="l00146"></a><span class="lineno">  146</span><span class="comment">   * tcp_westwood.c) also cause the obsolescence of m_rtt_min.  We don&#39;t invalidate it now, since we</span></div>
<div class="line"><a id="l00147" name="l00147"></a><span class="lineno">  147</span><span class="comment">   * don&#39;t have a better guess yet, but we do set m_reset_rtt_min, which will cause the next RTT</span></div>
<div class="line"><a id="l00148" name="l00148"></a><span class="lineno">  148</span><span class="comment">   * measurement to override any existing minimum.</span></div>
<div class="line"><a id="l00149" name="l00149"></a><span class="lineno">  149</span><span class="comment">   *</span></div>
<div class="line"><a id="l00150" name="l00150"></a><span class="lineno">  150</span><span class="comment">   * Should we also reset the bandwidth estimator somehow?  The reference implementation does not,</span></div>
<div class="line"><a id="l00151" name="l00151"></a><span class="lineno">  151</span><span class="comment">   * so I won&#39;t either.  As data transfer picks up, the estimator should pick up any changes in</span></div>
<div class="line"><a id="l00152" name="l00152"></a><span class="lineno">  152</span><span class="comment">   * bandwidth gradually anyway, it seems.</span></div>
<div class="line"><a id="l00153" name="l00153"></a><span class="lineno">  153</span><span class="comment">   *</span></div>
<div class="line"><a id="l00154" name="l00154"></a><span class="lineno">  154</span><span class="comment">   * Other comments from Congestion_control_classic&#39;s same spot apply here. */</span></div>
<div class="line"><a id="l00155" name="l00155"></a><span class="lineno">  155</span> </div>
<div class="line"><a id="l00156" name="l00156"></a><span class="lineno">  156</span>  <span class="comment">// Determine SSTHRESH.</span></div>
<div class="line"><a id="l00157" name="l00157"></a><span class="lineno">  157</span> </div>
<div class="line"><a id="l00158" name="l00158"></a><span class="lineno">  158</span>  <span class="keyword">const</span> <span class="keywordtype">size_t</span> new_slow_start_thresh_bytes = <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a9650086c28de7e9ed9fdaecaf9f183a6">congestion_window_adjusted_bytes</a>();</div>
<div class="line"><a id="l00159" name="l00159"></a><span class="lineno">  159</span> </div>
<div class="line"><a id="l00160" name="l00160"></a><span class="lineno">  160</span>  <span class="keyword">const</span> <a class="code hl_typedef" href="classflow_1_1util_1_1Shared__ptr__alias__holder.html#aef7998db71c60eeb5d1e3d1a97c14886">Peer_socket::Const_ptr</a> sock = <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a3e9786f9e5f170ca23135a2a815bc3f4">socket</a>();</div>
<div class="line"><a id="l00161" name="l00161"></a><span class="lineno">  161</span>  <a class="code hl_define" href="log_8hpp.html#affcf2e4c496ce3f42adf981669c623b8">FLOW_LOG_TRACE</a>(<span class="stringliteral">&quot;cong_ctl|bw_est [&quot;</span> &lt;&lt; sock &lt;&lt; <span class="stringliteral">&quot;] update: DTO event; set sl_st_thresh &quot;</span></div>
<div class="line"><a id="l00162" name="l00162"></a><span class="lineno">  162</span>                 <span class="stringliteral">&quot;to [&quot;</span> &lt;&lt; sock-&gt;bytes_blocks_str(new_slow_start_thresh_bytes) &lt;&lt; <span class="stringliteral">&quot;]; &quot;</span></div>
<div class="line"><a id="l00163" name="l00163"></a><span class="lineno">  163</span>                 <span class="stringliteral">&quot;cong_wnd to minimal value; schedule rtt_min reset.&quot;</span>);</div>
<div class="line"><a id="l00164" name="l00164"></a><span class="lineno">  164</span> </div>
<div class="line"><a id="l00165" name="l00165"></a><span class="lineno">  165</span>  <span class="comment">// Now set SSTHRESH and let m_classic_data set CWND to a low value (common to most congestion control strategies).</span></div>
<div class="line"><a id="l00166" name="l00166"></a><span class="lineno">  166</span> </div>
<div class="line"><a id="l00167" name="l00167"></a><span class="lineno">  167</span>  <span class="comment">// Will log but not enough (so log the above).</span></div>
<div class="line"><a id="l00168" name="l00168"></a><span class="lineno">  168</span>  <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#aeb3b683eed3fcd8af27323fc747abb03">m_classic_data</a>.<a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a63316b5d9e9a27816b09bb52c464b588">on_drop_timeout</a>(new_slow_start_thresh_bytes);</div>
<div class="line"><a id="l00169" name="l00169"></a><span class="lineno">  169</span> </div>
<div class="line"><a id="l00170" name="l00170"></a><span class="lineno">  170</span>  <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a5b3a333ae29bd009cd22919c1e01c19f">m_reset_rtt_min</a> = <span class="keyword">true</span>; <span class="comment">// As explained above.</span></div>
<div class="line"><a id="l00171" name="l00171"></a><span class="lineno">  171</span>} <span class="comment">// Congestion_control_classic_with_bandwidth_est::on_drop_timeout()</span></div>
<div class="line"><a id="l00172" name="l00172"></a><span class="lineno">  172</span> </div>
<div class="line"><a id="l00173" name="l00173"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a9650086c28de7e9ed9fdaecaf9f183a6">  173</a></span><span class="keywordtype">size_t</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a9650086c28de7e9ed9fdaecaf9f183a6">Congestion_control_classic_with_bandwidth_est::congestion_window_adjusted_bytes</a>()<span class="keyword"> const</span></div>
<div class="line"><a id="l00174" name="l00174"></a><span class="lineno">  174</span><span class="keyword"></span>{</div>
<div class="line"><a id="l00175" name="l00175"></a><span class="lineno">  175</span>  <span class="keyword">using </span>std::max;</div>
<div class="line"><a id="l00176" name="l00176"></a><span class="lineno">  176</span> </div>
<div class="line"><a id="l00177" name="l00177"></a><span class="lineno">  177</span>  <span class="keyword">using </span>Time_unit = <a class="code hl_typedef" href="classflow_1_1net__flow_1_1Send__bandwidth__estimator.html#a1e5e59588c6683d56866e49e5fd2980e">Send_bandwidth_estimator::Time_unit</a>;</div>
<div class="line"><a id="l00178" name="l00178"></a><span class="lineno">  178</span>  <span class="keyword">using </span>n_bytes_t = <a class="code hl_typedef" href="classflow_1_1net__flow_1_1Send__bandwidth__estimator.html#a40993b2699c5e8ab69dfd56e57ecdd28">Send_bandwidth_estimator::n_bytes_t</a>;</div>
<div class="line"><a id="l00179" name="l00179"></a><span class="lineno">  179</span> </div>
<div class="line"><a id="l00180" name="l00180"></a><span class="lineno">  180</span>  <span class="keyword">const</span> <a class="code hl_typedef" href="classflow_1_1util_1_1Shared__ptr__alias__holder.html#aef7998db71c60eeb5d1e3d1a97c14886">Peer_socket::Const_ptr</a> sock = <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a3e9786f9e5f170ca23135a2a815bc3f4">socket</a>();</div>
<div class="line"><a id="l00181" name="l00181"></a><span class="lineno">  181</span> </div>
<div class="line"><a id="l00182" name="l00182"></a><span class="lineno">  182</span>  <span class="comment">/* The basic formula is CWND = B * RTTmin.  Units and arithmetic are as follows.  B is in units of</span></div>
<div class="line"><a id="l00183" name="l00183"></a><span class="lineno">  183</span><span class="comment">   * bytes per Time_unit(1).  (The selection of Time_unit(1) is discussed in detail in that</span></div>
<div class="line"><a id="l00184" name="l00184"></a><span class="lineno">  184</span><span class="comment">   * alias&#39;s doc header.)  RTTmin, accordingly, is in units of Time_unit.  Therefore we can simply</span></div>
<div class="line"><a id="l00185" name="l00185"></a><span class="lineno">  185</span><span class="comment">   * multiply the two values.</span></div>
<div class="line"><a id="l00186" name="l00186"></a><span class="lineno">  186</span><span class="comment">   *</span></div>
<div class="line"><a id="l00187" name="l00187"></a><span class="lineno">  187</span><span class="comment">   * Range issues: B is returned in n_bytes_t, which is potentially larger than size_t due to</span></div>
<div class="line"><a id="l00188" name="l00188"></a><span class="lineno">  188</span><span class="comment">   * Send_bandwidth_estimator choosing to store safer internal values that way and return them in</span></div>
<div class="line"><a id="l00189" name="l00189"></a><span class="lineno">  189</span><span class="comment">   * that format also.  After the multiplication we convert the result to size_t; assuming</span></div>
<div class="line"><a id="l00190" name="l00190"></a><span class="lineno">  190</span><span class="comment">   * reasonable bandwidths, this number should not overflow even a 32-bit size_t.  However B can</span></div>
<div class="line"><a id="l00191" name="l00191"></a><span class="lineno">  191</span><span class="comment">   * also be zero (either unavailable or just a very low bandwidth).  As is standard, put a floor of</span></div>
<div class="line"><a id="l00192" name="l00192"></a><span class="lineno">  192</span><span class="comment">   * 2 max-block-sizes on it to avoid craziness. */</span></div>
<div class="line"><a id="l00193" name="l00193"></a><span class="lineno">  193</span> </div>
<div class="line"><a id="l00194" name="l00194"></a><span class="lineno">  194</span>  <span class="keyword">const</span> n_bytes_t bytes_per_time = sock-&gt;m_snd_bandwidth_estimator-&gt;bandwidth_bytes_per_time();</div>
<div class="line"><a id="l00195" name="l00195"></a><span class="lineno">  195</span> </div>
<div class="line"><a id="l00196" name="l00196"></a><span class="lineno">  196</span>  <span class="keyword">const</span> <span class="keywordtype">size_t</span> floor_wnd_bytes = 2 * sock-&gt;max_block_size();</div>
<div class="line"><a id="l00197" name="l00197"></a><span class="lineno">  197</span>  <span class="keyword">const</span> <span class="keywordtype">size_t</span> new_wnd_bytes = max(<span class="keywordtype">size_t</span>(bytes_per_time * <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#aac8260cf710dc42843a478873ed8b649">m_rtt_min</a>.count()),</div>
<div class="line"><a id="l00198" name="l00198"></a><span class="lineno">  198</span>                                   floor_wnd_bytes);</div>
<div class="line"><a id="l00199" name="l00199"></a><span class="lineno">  199</span> </div>
<div class="line"><a id="l00200" name="l00200"></a><span class="lineno">  200</span>  <a class="code hl_define" href="log_8hpp.html#affcf2e4c496ce3f42adf981669c623b8">FLOW_LOG_TRACE</a>(<span class="stringliteral">&quot;cong_ctl|bw_est [&quot;</span> &lt;&lt; sock &lt;&lt; <span class="stringliteral">&quot;] info: window calculation: wnd &quot;</span></div>
<div class="line"><a id="l00201" name="l00201"></a><span class="lineno">  201</span>                 <span class="stringliteral">&quot;= bw x rtt_min = [&quot;</span> &lt;&lt; sock-&gt;bytes_blocks_str(<span class="keywordtype">size_t</span>(bytes_per_time)) &lt;&lt; <span class="stringliteral">&quot;] bytes &quot;</span></div>
<div class="line"><a id="l00202" name="l00202"></a><span class="lineno">  202</span>                 <span class="stringliteral">&quot;per [&quot;</span> &lt;&lt; Time_unit(1) &lt;&lt; <span class="stringliteral">&quot;] x [&quot;</span> &lt;&lt; <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#aac8260cf710dc42843a478873ed8b649">m_rtt_min</a> &lt;&lt; <span class="stringliteral">&quot;] &quot;</span></div>
<div class="line"><a id="l00203" name="l00203"></a><span class="lineno">  203</span>                 <span class="stringliteral">&quot;(subject to floor [&quot;</span> &lt;&lt; sock-&gt;bytes_blocks_str(floor_wnd_bytes) &lt;&lt; <span class="stringliteral">&quot;]) &quot;</span></div>
<div class="line"><a id="l00204" name="l00204"></a><span class="lineno">  204</span>                 <span class="stringliteral">&quot;= [&quot;</span> &lt;&lt; sock-&gt;bytes_blocks_str(new_wnd_bytes) &lt;&lt; <span class="stringliteral">&quot;].&quot;</span>);</div>
<div class="line"><a id="l00205" name="l00205"></a><span class="lineno">  205</span> </div>
<div class="line"><a id="l00206" name="l00206"></a><span class="lineno">  206</span>  <span class="keywordflow">return</span> new_wnd_bytes;</div>
<div class="line"><a id="l00207" name="l00207"></a><span class="lineno">  207</span>}</div>
<div class="line"><a id="l00208" name="l00208"></a><span class="lineno">  208</span> </div>
<div class="line"><a id="l00209" name="l00209"></a><span class="lineno"><a class="line" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a461064f1ff0303cded61131df593599a">  209</a></span><span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a461064f1ff0303cded61131df593599a">Congestion_control_classic_with_bandwidth_est::on_idle_timeout</a>() <span class="comment">// Virtual.</span></div>
<div class="line"><a id="l00210" name="l00210"></a><span class="lineno">  210</span>{</div>
<div class="line"><a id="l00211" name="l00211"></a><span class="lineno">  211</span>  <span class="comment">/* Node has detected that nothing has been sent out by us for a while.  (Note that this is</span></div>
<div class="line"><a id="l00212" name="l00212"></a><span class="lineno">  212</span><span class="comment">   * different from a Drop Timeout.  A Drop Timeout causes data to be sent (either retransmitted [if</span></div>
<div class="line"><a id="l00213" name="l00213"></a><span class="lineno">  213</span><span class="comment">   * used] or new data), which resets the state back to non-idle for a while.)</span></div>
<div class="line"><a id="l00214" name="l00214"></a><span class="lineno">  214</span><span class="comment">   *</span></div>
<div class="line"><a id="l00215" name="l00215"></a><span class="lineno">  215</span><span class="comment">   * Do the same thing as Congestion_control_classic.</span></div>
<div class="line"><a id="l00216" name="l00216"></a><span class="lineno">  216</span><span class="comment">   *</span></div>
<div class="line"><a id="l00217" name="l00217"></a><span class="lineno">  217</span><span class="comment">   * It might actually seem like we should perhaps reset m_rtt_min here or reset the bandwidth</span></div>
<div class="line"><a id="l00218" name="l00218"></a><span class="lineno">  218</span><span class="comment">   * estimation, but the reference implementation (tcp_westwood.c in Linux) does no such thing on</span></div>
<div class="line"><a id="l00219" name="l00219"></a><span class="lineno">  219</span><span class="comment">   * idle timeout.  For m_rtt_min it does make sense to me; there&#39;s no reason to necessarily think</span></div>
<div class="line"><a id="l00220" name="l00220"></a><span class="lineno">  220</span><span class="comment">   * that just because the user hasn&#39;t sent anything in a while that the properties of the pipe</span></div>
<div class="line"><a id="l00221" name="l00221"></a><span class="lineno">  221</span><span class="comment">   * have changed.  For the bandwidth estimator, it also seems like some guess is better than no</span></div>
<div class="line"><a id="l00222" name="l00222"></a><span class="lineno">  222</span><span class="comment">   * guess, and as traffic picks up the data should correct itself gradually, but it&#39;s iffier.</span></div>
<div class="line"><a id="l00223" name="l00223"></a><span class="lineno">  223</span><span class="comment">   * Anyway, go with the reference implementation for now. */</span></div>
<div class="line"><a id="l00224" name="l00224"></a><span class="lineno">  224</span> </div>
<div class="line"><a id="l00225" name="l00225"></a><span class="lineno">  225</span>  <a class="code hl_variable" href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#aeb3b683eed3fcd8af27323fc747abb03">m_classic_data</a>.<a class="code hl_function" href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#afbe0609319f117e90074e1241abbba5c">on_idle_timeout</a>();</div>
<div class="line"><a id="l00226" name="l00226"></a><span class="lineno">  226</span>} <span class="comment">// Congestion_control_classic_with_bandwidth_est::on_idle_timeout()</span></div>
<div class="line"><a id="l00227" name="l00227"></a><span class="lineno">  227</span> </div>
<div class="line"><a id="l00228" name="l00228"></a><span class="lineno">  228</span>} <span class="comment">// namespace flow::net_flow</span></div>
<div class="ttc" id="aclassflow_1_1log_1_1Logger_html"><div class="ttname"><a href="classflow_1_1log_1_1Logger.html">flow::log::Logger</a></div><div class="ttdoc">Interface that the user should implement, passing the implementing Logger into logging classes (Flow'...</div><div class="ttdef"><b>Definition:</b> <a href="log_8hpp_source.html#l01280">log.hpp:1284</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_a63316b5d9e9a27816b09bb52c464b588"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a63316b5d9e9a27816b09bb52c464b588">flow::net_flow::Congestion_control_classic_data::on_drop_timeout</a></div><div class="ttdeci">void on_drop_timeout(size_t new_slow_start_thresh_bytes)</div><div class="ttdoc">Adjust state, including CWND and SSTHRESH, assuming a Drop Timeout just occurred.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8cpp_source.html#l00293">cong_ctl_util.cpp:293</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_a79e85a67e583b74cc414524d53650892"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#a79e85a67e583b74cc414524d53650892">flow::net_flow::Congestion_control_classic_data::on_congestion_event</a></div><div class="ttdeci">void on_congestion_event(size_t new_slow_start_thresh_bytes, size_t new_cong_wnd_bytes)</div><div class="ttdoc">Sets internally stored SSHTRESH and CWND to the given values; appropriately resets internal state so ...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8cpp_source.html#l00228">cong_ctl_util.cpp:228</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_ab3e34468efdf4d9e5b29eceb1fe84665"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#ab3e34468efdf4d9e5b29eceb1fe84665">flow::net_flow::Congestion_control_classic_data::on_acks</a></div><div class="ttdeci">void on_acks(size_t bytes)</div><div class="ttdoc">Adjusts state, including potentially CWND, based on either &quot;congestion avoidance&quot; or &quot;slow start&quot; alg...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8cpp_source.html#l00076">cong_ctl_util.cpp:76</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_adbda0ed3747b1eea62f4d790c37dbe46"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#adbda0ed3747b1eea62f4d790c37dbe46">flow::net_flow::Congestion_control_classic_data::congestion_window_bytes</a></div><div class="ttdeci">size_t congestion_window_bytes() const</div><div class="ttdoc">Return current stored CWND value in bytes.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8cpp_source.html#l00061">cong_ctl_util.cpp:61</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__data_html_afbe0609319f117e90074e1241abbba5c"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__data.html#afbe0609319f117e90074e1241abbba5c">flow::net_flow::Congestion_control_classic_data::on_idle_timeout</a></div><div class="ttdeci">void on_idle_timeout()</div><div class="ttdoc">Adjust state, namely CWND, assuming an Idle Timeout just occurred.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__util_8cpp_source.html#l00312">cong_ctl_util.cpp:312</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est_html_a07b264d895ef7eb343d6d503d12e63d0"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a07b264d895ef7eb343d6d503d12e63d0">flow::net_flow::Congestion_control_classic_with_bandwidth_est::S_INIT_RTT_MIN</a></div><div class="ttdeci">static const Send_bandwidth_estimator::Time_unit S_INIT_RTT_MIN</div><div class="ttdoc">The initial value for m_rtt_min, until one RTT measurement comes in.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__classic__bw_8hpp_source.html#l00182">cong_ctl_classic_bw.hpp:182</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est_html_a3358f8b8700d5427a5163f2f480b2e8d"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a3358f8b8700d5427a5163f2f480b2e8d">flow::net_flow::Congestion_control_classic_with_bandwidth_est::on_drop_timeout</a></div><div class="ttdeci">void on_drop_timeout(size_t bytes, size_t packets) override</div><div class="ttdoc">Implements Congestion_control_strategy::on_drop_timeout() API.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__classic__bw_8cpp_source.html#l00137">cong_ctl_classic_bw.cpp:137</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est_html_a461064f1ff0303cded61131df593599a"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a461064f1ff0303cded61131df593599a">flow::net_flow::Congestion_control_classic_with_bandwidth_est::on_idle_timeout</a></div><div class="ttdeci">void on_idle_timeout() override</div><div class="ttdoc">Implements Congestion_control_strategy::on_idle_timeout() API.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__classic__bw_8cpp_source.html#l00209">cong_ctl_classic_bw.cpp:209</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est_html_a5b3a333ae29bd009cd22919c1e01c19f"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a5b3a333ae29bd009cd22919c1e01c19f">flow::net_flow::Congestion_control_classic_with_bandwidth_est::m_reset_rtt_min</a></div><div class="ttdeci">bool m_reset_rtt_min</div><div class="ttdoc">If true, then when the next RTT measurement comes in, any past measurement should be disregarded,...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__classic__bw_8hpp_source.html#l00201">cong_ctl_classic_bw.hpp:201</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est_html_a83ee8438d6033c26a6af03b9dd173dc3"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a83ee8438d6033c26a6af03b9dd173dc3">flow::net_flow::Congestion_control_classic_with_bandwidth_est::on_acks</a></div><div class="ttdeci">void on_acks(size_t bytes, size_t packets) override</div><div class="ttdoc">Implements Congestion_control_strategy::on_acks() API.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__classic__bw_8cpp_source.html#l00096">cong_ctl_classic_bw.cpp:96</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est_html_a8d0e32a67aa333ab15a5b166a2913260"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a8d0e32a67aa333ab15a5b166a2913260">flow::net_flow::Congestion_control_classic_with_bandwidth_est::on_individual_ack</a></div><div class="ttdeci">void on_individual_ack(const Fine_duration &amp;packet_rtt, const size_t bytes, const size_t sent_cwnd_bytes) override</div><div class="ttdoc">Implements Congestion_control_strategy::on_individual_ack() API.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__classic__bw_8cpp_source.html#l00050">cong_ctl_classic_bw.cpp:51</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est_html_a942ce2561d6d2bbbb8faa8160a772416"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a942ce2561d6d2bbbb8faa8160a772416">flow::net_flow::Congestion_control_classic_with_bandwidth_est::on_loss_event</a></div><div class="ttdeci">void on_loss_event(size_t bytes, size_t packets) override</div><div class="ttdoc">Implements Congestion_control_strategy::on_loss_event() API.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__classic__bw_8cpp_source.html#l00103">cong_ctl_classic_bw.cpp:103</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est_html_a9650086c28de7e9ed9fdaecaf9f183a6"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#a9650086c28de7e9ed9fdaecaf9f183a6">flow::net_flow::Congestion_control_classic_with_bandwidth_est::congestion_window_adjusted_bytes</a></div><div class="ttdeci">size_t congestion_window_adjusted_bytes() const</div><div class="ttdoc">Returns the best bandwidth/latency-based guess for what the current window (pipe) size should be.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__classic__bw_8cpp_source.html#l00173">cong_ctl_classic_bw.cpp:173</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est_html_aac8260cf710dc42843a478873ed8b649"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#aac8260cf710dc42843a478873ed8b649">flow::net_flow::Congestion_control_classic_with_bandwidth_est::m_rtt_min</a></div><div class="ttdeci">Send_bandwidth_estimator::Time_unit m_rtt_min</div><div class="ttdoc">The minimum individual packet's RTT observed so far; it should be reset to the next sample if m_reset...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__classic__bw_8hpp_source.html#l00194">cong_ctl_classic_bw.hpp:194</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est_html_ad0090c57a7877701be584c006c9db329"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#ad0090c57a7877701be584c006c9db329">flow::net_flow::Congestion_control_classic_with_bandwidth_est::Congestion_control_classic_with_bandwidth_est</a></div><div class="ttdeci">Congestion_control_classic_with_bandwidth_est(log::Logger *logger_ptr, Peer_socket::Const_ptr sock)</div><div class="ttdoc">Constructs object by setting up logging and saving a pointer to the containing Peer_socket.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__classic__bw_8cpp_source.html#l00031">cong_ctl_classic_bw.cpp:32</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est_html_aeb3b683eed3fcd8af27323fc747abb03"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#aeb3b683eed3fcd8af27323fc747abb03">flow::net_flow::Congestion_control_classic_with_bandwidth_est::m_classic_data</a></div><div class="ttdeci">Congestion_control_classic_data m_classic_data</div><div class="ttdoc">The Reno CWND/SSTHRESH-changing engine and CWND/SSTHRESH storage.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__classic__bw_8hpp_source.html#l00187">cong_ctl_classic_bw.hpp:187</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est_html_af49a3fe6d8bb1ec32ac245faed17e842"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__classic__with__bandwidth__est.html#af49a3fe6d8bb1ec32ac245faed17e842">flow::net_flow::Congestion_control_classic_with_bandwidth_est::congestion_window_bytes</a></div><div class="ttdeci">size_t congestion_window_bytes() const override</div><div class="ttdoc">Implements Congestion_control_strategy::congestion_window_bytes() API.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl__classic__bw_8cpp_source.html#l00045">cong_ctl_classic_bw.cpp:45</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__strategy_html"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__strategy.html">flow::net_flow::Congestion_control_strategy</a></div><div class="ttdoc">The abstract interface for a per-socket module that determines the socket's congestion control behavi...</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl_8hpp_source.html#l00176">cong_ctl.hpp:180</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Congestion__control__strategy_html_a3e9786f9e5f170ca23135a2a815bc3f4"><div class="ttname"><a href="classflow_1_1net__flow_1_1Congestion__control__strategy.html#a3e9786f9e5f170ca23135a2a815bc3f4">flow::net_flow::Congestion_control_strategy::socket</a></div><div class="ttdeci">Peer_socket::Const_ptr socket() const</div><div class="ttdoc">Utility for subclasses that returns a handle to the containing Peer_socket.</div><div class="ttdef"><b>Definition:</b> <a href="cong__ctl_8cpp_source.html#l00063">cong_ctl.cpp:63</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Send__bandwidth__estimator_html_a1e5e59588c6683d56866e49e5fd2980e"><div class="ttname"><a href="classflow_1_1net__flow_1_1Send__bandwidth__estimator.html#a1e5e59588c6683d56866e49e5fd2980e">flow::net_flow::Send_bandwidth_estimator::Time_unit</a></div><div class="ttdeci">boost::chrono::milliseconds Time_unit</div><div class="ttdoc">The primary time unit over which this class reports bandwidth.</div><div class="ttdef"><b>Definition:</b> <a href="bandwidth_8hpp_source.html#l00167">bandwidth.hpp:167</a></div></div>
<div class="ttc" id="aclassflow_1_1net__flow_1_1Send__bandwidth__estimator_html_a40993b2699c5e8ab69dfd56e57ecdd28"><div class="ttname"><a href="classflow_1_1net__flow_1_1Send__bandwidth__estimator.html#a40993b2699c5e8ab69dfd56e57ecdd28">flow::net_flow::Send_bandwidth_estimator::n_bytes_t</a></div><div class="ttdeci">uint64_t n_bytes_t</div><div class="ttdoc">Type that represents the number of bytes, either as an absolute amount or over some time period.</div><div class="ttdef"><b>Definition:</b> <a href="bandwidth_8hpp_source.html#l00134">bandwidth.hpp:134</a></div></div>
<div class="ttc" id="aclassflow_1_1util_1_1Shared__ptr__alias__holder_html_aef7998db71c60eeb5d1e3d1a97c14886"><div class="ttname"><a href="classflow_1_1util_1_1Shared__ptr__alias__holder.html#aef7998db71c60eeb5d1e3d1a97c14886">flow::util::Shared_ptr_alias_holder&lt; boost::shared_ptr&lt; Peer_socket &gt; &gt;::Const_ptr</a></div><div class="ttdeci">Const_target_ptr Const_ptr</div><div class="ttdoc">Short-hand for ref-counted pointer to immutable values of type Target_type::element_type (a-la T cons...</div><div class="ttdef"><b>Definition:</b> <a href="shared__ptr__alias__holder_8hpp_source.html#l00127">shared_ptr_alias_holder.hpp:127</a></div></div>
<div class="ttc" id="acong__ctl__classic__bw_8hpp_html"><div class="ttname"><a href="cong__ctl__classic__bw_8hpp.html">cong_ctl_classic_bw.hpp</a></div></div>
<div class="ttc" id="alog_8hpp_html_affcf2e4c496ce3f42adf981669c623b8"><div class="ttname"><a href="log_8hpp.html#affcf2e4c496ce3f42adf981669c623b8">FLOW_LOG_TRACE</a></div><div class="ttdeci">#define FLOW_LOG_TRACE(ARG_stream_fragment)</div><div class="ttdoc">Logs a TRACE message into flow::log::Logger *get_logger() with flow::log::Component get_log_component...</div><div class="ttdef"><b>Definition:</b> <a href="log_8hpp_source.html#l00227">log.hpp:227</a></div></div>
<div class="ttc" id="anamespaceflow_1_1net__flow_html"><div class="ttname"><a href="namespaceflow_1_1net__flow.html">flow::net_flow</a></div><div class="ttdoc">Flow module containing the API and implementation of the Flow network protocol, a TCP-inspired stream...</div><div class="ttdef"><b>Definition:</b> <a href="asio_2node_8cpp_source.html#l00024">node.cpp:25</a></div></div>
<div class="ttc" id="anamespaceflow_html_a48799f1263cdeedec125be51a3db2b79"><div class="ttname"><a href="namespaceflow.html#a48799f1263cdeedec125be51a3db2b79">flow::Fine_duration</a></div><div class="ttdeci">Fine_clock::duration Fine_duration</div><div class="ttdoc">A high-res time duration as computed from two Fine_time_pts.</div><div class="ttdef"><b>Definition:</b> <a href="common_8hpp_source.html#l00416">common.hpp:416</a></div></div>
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